Starter for heavy-oil engines



Sept. 5, 1950 L. SAIVES STARTER FOR HEAVY on mamas Filed Dec. 10, 1947 INVENTOR L EON SAW ES ATTORNEY Patented Sept. 5, 1950 STARTER FOR HEAVY-01L ENGINES Leon Saives, Billancourt, France, assignor to Reglc Nationale Des Usines Renault, Biilancourt,

France Application December 10, 1947, Serial No. 790,804 In France December 10, 1946 2 Claims. (01. zoo-as) This invention relates to an improvement in electric starters for heavy-oil engines, and concerns the type of device in which a driving pinion acting on the starter is engaged by the displacement of the armature.

Owing to the fact that a considerable power is required to start heavy oil engines, a progressive action is generally aimed at and two stages are involved in making the starter develop itsiull power. I

In the first stage, the aforesaid pinion is brought into engagement at low power. When this engagement has been eflected, the displacement of the armature operates a contact which closes the circuit of the exciting coil of an electromagnet contact maker and thus enables the starter to develop its full power, this phase constituting the second stage.

In the majority of starters actin by the displacement of the armature which are at present in use, the operation of the starter button ensures, on the one hand, the feeding of an auxiliary series winding of small section in order to complete the first stage, and on the other hand the feeding of the exciting coil of an electro-magnetic contact maker, the circuit of which is only closed by a suitable contact for the second stage when the armature has been displaced and has eilected the engagement of the pinion.

According to the present invention, the auxiliary series field winding is replaced by a shunt field winding which will have the effect of moving the armature longitudinally, in its frame while the rotation of the armature at low speed for efiecting the displacement of the pinion in the first stage is effected by feeding it through a resistance which will be short-circuited in the second stage at the moment when, the engagement of the pinion having been effected, the starter can develop its full power. The auxiliary shunt winding retains its full effectiveness, so that it is a question of a compound motor and not of a series motor, which affords many disadvantages as wil1 hereinafter be explained.

In the accompanying drawing, the figure represents the installation according to the invention.

According to the present invention (Figure 2) the series winding 2 is replaced by a shunt winding 2 The elements I, 3, 4, 5 and 6 act durin the first starting stage as in the preceding known case. A resistance 8 connected across the starter button I and the field winding 1. and armature 3 enables the starter to be made to function at reduced power during the first stage, the auxiliary shunt winding 2 being simultaneously excited. For the second stage, as in the case oi Figure l, the contact 4 closes when the pinion is in engage ment, thus exciting the coil of the contact maker 6, the closing of which short-circuits the resistance 8. The principal winding I is then fed at the same time as the secondary winding 2 at the nominal voltage of the accumulator battery. The starter turns at full power and functions in compound under the simultaneous action of the winding 1 and of the auxiliary winding 2 which retains its full eflfectiveness.

The replacement of the auxiliary series winding by a shunt winding affords the following advantages:

(1) Increase of the useful power-to-weight ratio of the starter and consequently of its output, the shunt winding 2 which is always under the battery voltage (Figure 2) always being very, effective during the starting, while the series winding of small section (Figure l) is substantially ineffective, being short circuited by the series winding of large section 1.

(2) This device prevents the automatic returns of the armature to its inoperative position and consequently the disengagement of the pinion, while the heavy-oil engine tends only to start, the current absorbed by the starter at this instant not being sufficient to ensure the maintenance of the armature in its frame, since the series winding of large section has by construction only a small number of turns.

(3) It renders possible a smoother engagement of the pinion. It is possible, in fact, to act on the two variables that is to say, the thrust of the armature and the speed of rotation of the armature, by means of the resistance of the shunt winding 2 and the resistance 8 (Figure 2). With the series windin 2 (Figure 1) the action is more delicate, because in the endeavour to increase the thrust of the armature its speed of rotation is increased, which has a bad eifect on the correct engagement of the pinion.

(4) It prevents racing of the armature during no-load,running, since the motor is a compound motor and not a series motor.

I claim:

1. In a two stage starter for internal combustion motors, the. combination comprising an axially movable armature for driving a pinion for engagement with the starter, a main series field winding for said armature, an auxiliary shunt field winding for the armature to effect an axial movement thereof, a source of energizing potential, switch means for providing circuits respec- I 3 tiveLv from said source to said au'xiiiary and said main fields, said circuit to said main field inciuding a voltage dropping resistance whereby an initial slow rotation of the armature by the main iieid is effected during the axial movement of said armature.

2. The starter combination according to claim 1, further including means for short 'circuiting said dropping resistance, and means for actuating said shorting means including an electromagnetic contactor and a. circuit therefor, and a contact in said last named circuit operated by the conclusion of the axial movement of said arms.- ture whereby upon said pinion engaging the starter, the armature is driven with full power.

LEON SAIVES.

4 nsrnnnuczs mm The following references are of record in the iiie of this patent:

UNITED STATES PATENTS France July 15, 1936 

